Coke powder filtration system for quenching system in ethylene plant

Abstract

This utility model relates to a coke powder filtration system for a quench system in an ethylene plant, comprising: a quench tower; a quench water return pipeline connected to the bottom of the quench tower, wherein a quench water circulation pump is installed on the quench water return pipeline; a main quench water filter located on the quench water return pipeline and downstream of the quench water circulation pump; and a secondary quench water filter equipped with a coalescing filter element located downstream of the main quench water filter. The top of the main quench water filter is connected to the bottom inlet of the secondary quench water filter via a first pipeline, and the top outlet of the secondary quench water filter is connected to the return inlet of the quench tower via a second pipeline. The advantage is that it can effectively filter coke powder from the quench water, thereby ensuring the long-term stable operation of the quench water system.

Description

Technical Field

[0001] This utility model relates to the field of ethylene plant technology, and in particular to a coke powder filtration system for a quenching system of an ethylene plant. Background Technology

[0002] Currently, the feedstocks for domestic ethylene plants are mainly divided into two types: heavy feedstocks and light feedstocks. Heavy feedstocks include naphtha, hydrotreated tail oil, and topping oil; light feedstocks mainly include ethane, propane, and LPG. For heavy feedstocks, the separation and cooling method used in the post-cracking system is a series operation of quench oil towers and quench water towers. For light feedstocks, most plants directly use quench water towers for cooling and separation. Currently, most domestic and international ethylene plants tend to use light feedstocks for cracking, as this is more profitable than using heavy feedstocks. For ethylene plants that only operate with quench water towers (without quench oil towers), maintaining the normal long-term operation of the quench water system is particularly important.

[0003] Because high-temperature cracking of hydrocarbons produces coke, some of which enters the quench water system as fine powder (coke dust) along with the cracked gas. Therefore, a key factor in maintaining the normal, long-term stable operation of the quench water system is the effective capture and filtration of coke dust. Existing filtration methods generally involve installing a coke catcher after the primary and tertiary quench coolers in each cracking furnace, as well as corresponding filters in the quench water tower return pipeline. However, existing quench water auxiliary filters are mostly in the form of filter baskets, with a normal flow rate of about 300 t / h and a high-inlet, low-outlet water flow. Furthermore, due to the fineness of the coke dust, even after changing the filter baskets to multiple mesh sizes in actual production, it is still not possible to effectively filter out the coke dust, and the bottom of the large-mesh filter baskets is often easily damaged.

[0004] Therefore, the existing coke powder filtration system for the quenching system of ethylene plants needs further improvement. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a coke powder filtration system for ethylene plant quenching systems that can effectively filter coke powder in quenching water, thereby ensuring the long-term stable operation of the quenching water system, in light of the current state of the technology.

[0006] The technical solution adopted by this utility model to solve the above-mentioned technical problems is: a coke powder filtration system for a quenching system of an ethylene plant, comprising:

[0007] quench water tower;

[0008] A quench water return pipeline is connected to the bottom of the quench water tower, and a quench water circulation pump is installed on the quench water return pipeline.

[0009] The main filter for quench water is installed on the quench water return pipeline and is located downstream of the quench water circulation pump.

[0010] The quench water auxiliary filter, equipped with a coalescing filter element, is located downstream of the quench water main filter. The top of the quench water main filter is connected to the bottom inlet of the quench water auxiliary filter via a first pipeline, and the top outlet of the quench water auxiliary filter is connected to the return inlet of the quench water tower via a second pipeline.

[0011] As an improvement, the quench water auxiliary filter's drain outlet is connected to an underground tank via a drain pipeline. This pipeline directs coke residue to the underground tank, preventing system contamination. This design also supports online cleaning (without downtime), improving maintenance efficiency.

[0012] As an improvement, it also includes:

[0013] An oil-water separator, located downstream of the quench tower, is used to separate the oil-water mixture from the quench tower.

[0014] A stripping tower, located downstream of the oil-water separator, is used to strip the organic phase separated by the oil-water separator. The bottom of the stripping tower is connected to a discharge pipeline, which is equipped with a product transfer pump and a basket filter located upstream of the pump. The oil-water separator prioritizes separating coke powder from the oil phase, reducing impurities entering the stripping tower. The basket filter further traps coke powder at the stripping tower's discharge end, protecting the product transfer pump and improving product purity.

[0015] As an improvement, a control valve is installed on the discharge line of the stripping tower, and the basket filter is connected to the discharge line in parallel with the control valve. This design allows for filter isolation and maintenance without shutting down the tower, ensuring continuous operation.

[0016] As an improvement, the water phase outlet of the oil-water separator is also connected to an outlet pipeline for delivering water to the process water system.

[0017] Considering that a single filter set requires shutdown for cleaning or failure, affecting system stability, the main quench water filter and the auxiliary quench water filter constitute a quench water filter group, with two sets arranged in parallel. This parallel design achieves "one in use, one on standby," ensuring that switching does not affect the quench water circulation, improving system reliability, and supporting long-term uninterrupted operation.

[0018] Compared with existing technologies, the advantages of this invention are as follows: A secondary quench water filter with a coalescing filter element is installed after the main quench water filter in the quench system. This coalescing filter element can capture ultrafine coke powder (which traditional filter baskets cannot intercept) through adsorption-coalescing, thus improving filtration accuracy. The inlet and outlet pipes of the secondary quench water filter have also been modified, changing the original high-inlet, low-outlet configuration to a low-inlet, high-outlet configuration. This increases the effective filtration area while also increasing strength, making it less prone to breakage and enabling the filtration of more fine coke powder particles, thereby ensuring the normal, long-term, and stable operation of the quench water system. Attached Figure Description

[0019] Figure 1 This is a flowchart of a coke powder filtration system for a quenching system in an ethylene plant according to an embodiment of the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0021] In the specification and claims of this utility model, terms indicating direction, such as "front," "rear," "upper," "lower," "left," "right," "side," "top," and "bottom," are used to describe various exemplary structural parts and elements of this utility model. However, the use of these terms is merely for the purpose of explanation and is based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this utility model can be arranged in different orientations, these terms indicating direction are for illustrative purposes only and should not be regarded as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

[0022] Figure 1 This invention illustrates a preferred embodiment of a coke powder filtration system for a quenching system in an ethylene plant. The coke powder filtration system for a quenching system in this embodiment is used for quench water treatment in a light feedstock cracking unit, and mainly includes a quenching water tower 10, a quench water return pipeline 11, a quench water circulation pump 12, a main quench water filter 13, and a secondary quench water filter 14.

[0023] The quench tower 10 is used to treat the pyrolysis gas from the quench cooler upstream of the pyrolysis furnace. A quench water return pipeline 11 is located at the bottom of the quench tower 10, and a quench water circulation pump 12 is installed on this pipeline. The main filter 13 is a basket filter 33, installed downstream of the quench water circulation pump 12, used to intercept large coke particles. The secondary filter 14 is a coalescing filter, which generally includes a vertical tank structure with multiple layers of coalescing filter elements inside. The top outlet of the main filter 13 is connected to the bottom inlet of the secondary filter 14 via a first pipeline 151. The top outlet of the secondary filter 14 is connected to the return inlet in the middle of the quench tower 10 via a second pipeline 152. This "low inlet, high outlet" flow design allows water to penetrate the coalescing filter elements from bottom to top, and the coke particles are captured and coalesced into large particles deep within the filter elements before settling. The secondary filter 14 has a drain outlet at the bottom, connected to an underground collection tank via a drain pipeline 153.

[0024] The outlet of the main filter 13 can also be connected to a corresponding pipeline to distribute the system and provide quench water.

[0025] Considering that a single filter set requires shutdown for cleaning or failure, affecting system stability, the aforementioned main quench water filter 13 and auxiliary quench water filter 14 constitute a quench water filter group. In this embodiment, two quench water filter groups can be arranged in parallel. The parallel design achieves "one in use and one on standby," and the switching does not affect the quench water circulation, which can improve system reliability and support long-term uninterrupted operation.

[0026] Downstream of the quench tower 10, an oil-water separation system is also installed. Specifically, the vapor outlet at the top of the quench tower 10 is connected to an oil-water separator 20, which typically contains an inclined plate separator. The oil phase outlet of the oil-water separator 20 is connected to the feed inlet of the stripping tower 30 via a corresponding pipeline, on which a second liquid supply pump 222 is installed. The water phase outlet is connected to the process water system via a corresponding pipeline, on which a first liquid supply pump 221 is installed.

[0027] A product conveying pump 32 is installed on the bottom discharge pipeline 31 of the stripping tower 30, and a basket filter 33 is installed before the product conveying pump 32. The basket filter 33 is connected to the control valve 34 via a parallel bypass: during normal operation, the material flows through the filter; during maintenance, the gate valves before and after the filter are closed, and the material flows directly through the bypass control valve 34. Adding the basket filter 33 increases the filtration capacity and greatly extends the online operating time of a single pump.

[0028] The operation procedure of the coke powder filtration system for the ethylene plant quench system in this embodiment is as follows: Quenching water flowing from the bottom of the quench tower 10 is pressurized by the quench water circulation pump 12 and enters the main filter 13 for preliminary filtration, and then enters from the bottom of the auxiliary filter 14. When the water flows through the coalescing filter element, the ultrafine coke powder is adsorbed by the filter element fibers and agglomerates, eventually settling in the bottom chamber of the auxiliary filter 14. The purified quench water returns to the quench tower 10 from the top. When the auxiliary filter 14 needs to be cleaned, the corresponding drain valve can be opened, and the coke powder residue is discharged into the underground tank.

[0029] In this embodiment, a secondary quench water filter 14 with a coalescing filter element is installed after the main quench water filter 13 in the quench system. The coalescing filter element captures ultrafine coke powder (which traditional filter baskets cannot intercept) through adsorption-coalescing, improving filtration accuracy. The inlet and outlet pipes of the secondary quench water filter 14 have also been modified, changing the original high-inlet, low-outlet flow pattern to a low-inlet, high-outlet flow pattern. This increases the effective filtration area and also increases the filter's strength, making it less prone to breakage and enabling it to filter out more fine coke powder particles, thus ensuring the normal, long-term, and stable operation of the quench water system. The secondary quench water filter 14 adopts a "low-inlet, high-outlet" flow direction (bottom inlet → top outlet) design, causing coke powder to deposit at the bottom of the filter element rather than the top, reducing the risk of filter element clogging and breakage. The main and secondary filters 14 are connected in series to form a two-stage filtration system. The main filter 13 intercepts large particles, while the secondary filter 14 finely filters out fine powder, working together to extend the system's operating cycle.

Claims

1. A coke powder filtration system for a quenching system in an ethylene plant, comprising: Quench water tower(10); The quench water return pipeline (11) is connected to the bottom of the quench water tower (10), and the quench water return pipeline (11) is equipped with a quench water circulation pump (12). Its features also include: The main filter (13) for quench water is installed on the quench water return pipeline (11) and is located downstream of the quench water circulation pump (12); A secondary quench water filter (14) equipped with a coalescing filter element is located downstream of the main quench water filter (13). The top of the main quench water filter (13) is connected to the bottom inlet of the secondary quench water filter (14) via a first pipeline (151), and the top outlet of the secondary quench water filter (14) is connected to the return inlet of the quench water tower (10) via a second pipeline (152).

2. The coke breeze filtration system for ethylene plant quench system as claimed in claim 1 wherein: The drain outlet of the quench water auxiliary filter (14) is connected to the underground tank via a drain pipeline (153).

3. The coke breeze filtration system for ethylene plant quench system according to claim 1 or 2, characterized in that Also includes: An oil-water separator (20) is located downstream of the quench tower (10) and is used to separate the oil-water mixture from the quench tower (10). A stripping tower (30) is located downstream of the oil-water separator (20) and is used to strip the organic phase separated by the oil-water separator (20). The bottom of the stripping tower (30) is connected to a discharge pipeline (31), which is equipped with a product transfer pump (32) and a basket filter (33) located upstream of the product transfer pump (32).

4. The coke breeze filtration system for ethylene plant quench system as claimed in claim 3 wherein: The stripping tower (30) is equipped with a control valve (34) on its discharge pipeline (31), and the basket filter (33) is connected to the discharge pipeline (31) in parallel with the control valve (34).

5. The coke powder filtration system for the quenching system of an ethylene plant according to claim 3, characterized in that: The water phase outlet of the oil-water separator (20) is also connected to a water outlet pipeline (21) for sending water to the process water system.

6. The coke powder filtration system for the quenching system of an ethylene plant according to claim 1, characterized in that: The main quench water filter (13) and the auxiliary quench water filter (14) constitute a quench water filter group, and the quench water filter group has two sets arranged in parallel.

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